The present invention relates to a novel and useful panel door structure.
Doors are typically assembled from multiple components, such as stiles, which extend vertically and one or more rails, which traverse a pair of stiles to form a frame. Panels are often placed within this frame by the use of interlocking mortises and tenons and muntins which interpose the stiles. Generally, mechanical fasteners are then employed to retain the plurality of elements into a unitary door. The door is then finished according to esthetic criteria and installed with hardware such as hinges, door knobs, latches, locks, and the like.
Although doors have been traditionally constructed of wood, newer materials have proven satisfactory as a substitute for wood in this regard. For example, fibrous materials known as high-density fiber (HDF), medium density fiber (MDF), low-density fiber (LDF), and the like have been employed for this purpose.
In addition, newer methods of finishing involving relatively high heating processes have been applied to windows and doors. For example, powder coating is a preferred finish that is environmentally safe and is extremely durable. Unfortunately, conventionally assembled wooden doors are not amenable to powder coating since the interlocking elements and the fasteners employed in the construction of the door tend to separate upon the application of heat.
In the past, many doors have been devised from components which are fixed together using hardware such as screws, nails, clips, and the like. For example, U.S. Pat. Nos. 635,341, 2,699,578, 3,798,863, 5,737,890, and 6,311,454 illustrate doors of such construction.
U.S. Pat. No. 2,399,666 shows a reinforced door having a core insulating material. The door is held together by mechanical fasteners.
U.S. Patent Publication 2002/0124497 A1 describes a fire resistant door edge in which intumescent material is formed into a strip covered by an edge. The composite assembly is held together by a screw.
International Publication WO 02/31306 A1 describes a fire door in which intumescent material is placed along the edges of a door which is assembled using threaded fasteners.
U.S. Pat. No. 5,934,040 teaches a snap-together molded door in which foam is used as the core and pigment is provided in the material forming the portions of the door.
Panel door structure which is formed as a unitary member without mechanical fasteners, would constitute a notable advance in the construction arts.